Synthesis and structural study of polypyrroles prepared in the presence of surfactants

Conducting and stable polypyrrole (PPy) was synthesized by chemical oxidative polymerization of pyrrole in aqueous solution containing an oxidant, ferric sulfate, and a surfactant. Anionic surfactants: sodium dodecylbenzenesulfonate, dodecylbenzenesulfonic acid, sodium dodecyl sulfate, poly(ethylene oxide)-n-alkyl-3-sulfopropyl ether potassium salt; cationic surfactant: tetradecyltrimethylammonium bromide; and non-ionic surfactants: poly(ethylene oxide) (10) iso-octylphenyl ether (Triton® X-100), poly(ethylene oxide) (20) sorbitan monolaurate (Tween® 20) and poly(ethylene oxide) (20) sorbitan monostearate (Tween® 60) were used as additives. Results of the elemental analysis and FTIR spectroscopy proved that only the anionic surfactants were incorporated into PPy similarly as the doping anion. This leads to a better stability towards the deprotonation. Also thermal stability, checked by TGA in air, was improved. Scanning electron microscopy studies showed that the presence of the anionic surfactant strongly influenced the morphology of the polymer product.